UpdateProgress在图像上传后第二次不工作

Question

当btnSubmit点击时出现UpdateProgress，但在第二次上传图像后UpdateProgress不出现。如果我没有上传图像，则会显示更新进度。而且我还发现第二次图像上传后ContentPlaceHolder1_updProgress从控制台中消失。否则（第二次没有图像上传）ContentPlaceHolder1_updProgress在控制台中。所以我认为问题在于第二次图像上传。在我第一次点击时，每件事都可以。

我的aspx

<asp:UpdatePanel ID="UpdatePanel2" runat="server"> 
    <Triggers> 
     <asp:AsyncPostBackTrigger ControlID="btnSubmit" /> 
    </Triggers> 
    <ContentTemplate> 
     <div class="form-group row"> 
      <div class="col-sm-6"> 
       <p style="margin: 0 0 5px 0;"><b>Class</b></p> 
       <asp:DropDownList ID="drpClass" CssClass="form-control" OnSelectedIndexChanged="drpClass_SelectedIndexChanged" AutoPostBack="true" runat="server"></asp:DropDownList> 
      </div> 
      <div class="col-sm-6"> 
       <p style="margin: 0 0 5px 0;"><b>Division</b></p> 
       <asp:DropDownList ID="drpDiv" CssClass="form-control" 
        runat="server"> 
       </asp:DropDownList> 
      </div> 
     </div> 
     <div class="form-group row"> 
      <div class="col-sm-6"> 
       <p style="margin: 0 0 5px 0;"><b>Date</b></p> 
       <asp:TextBox runat="server" ID="txtDateGiven" CssClass="form-control" 
        placeholder="Select a Date"></asp:TextBox> 
       <asp:CalendarExtender ID="CalendarExtender2" runat="server" Format="dd/MMM/yyyy" PopupButtonID="txtDateGiven" 
        TargetControlID="txtDateGiven"> 
       </asp:CalendarExtender> 
      </div> 

      <div class="col-sm-6"> 
       <p style="margin: 0 0 5px 0;"><b>Date of Submission</b></p> 
       <asp:TextBox runat="server" ID="txtDateSubmit" CssClass="form-control" 
        placeholder="Select a Date"></asp:TextBox> 
       <asp:CalendarExtender ID="CalendarExtender1" runat="server" Format="dd/MMM/yyyy" PopupButtonID="txtDateSubmit" 
        TargetControlID="txtDateSubmit"> 
       </asp:CalendarExtender> 
      </div> 
     </div> 

     <div class="form-group row"> 
      <div class="col-sm-12"> 
       <p style="margin: 0 0 5px 0;"><b>Subject</b></p> 
       <asp:DropDownList ID="drpSubject" CssClass="form-control" runat="server"></asp:DropDownList> 
      </div> 
     </div> 
     <div class="form-group row"> 
      <div class="col-sm-12"> 
       <p style="margin: 0 0 5px 0;"><b>Type</b></p> 
       <asp:DropDownList ID="drpAssignmentType" CssClass="form-control" runat="server"></asp:DropDownList> 
      </div> 
     </div> 
     <div class="form-group row"> 
      <div class="col-sm-12"> 
       <p style="margin: 0 0 5px 0;"><b>Title</b></p> 
       <asp:TextBox ID="txtAssignmentTitle" CssClass="form-control" placeholder="Enter Title" 
        runat="server"></asp:TextBox> 
      </div> 
     </div> 
     <div class="form-group row"> 
      <div class="col-sm-12"> 
       <p style="margin: 0 0 5px 0;"><b>Description</b></p> 
       <asp:TextBox ID="txtAssignmentDes" CssClass="form-control" TextMode="MultiLine" Height="250" 
        placeholder="Enter Description" 
        runat="server"></asp:TextBox> 
      </div> 
     </div> 
    </ContentTemplate> 
</asp:UpdatePanel> 
<asp:UpdatePanel ID="UpdatePanel3" runat="server"> 
    <Triggers> 
     <asp:PostBackTrigger ControlID="btnUpload" /> 
    </Triggers> 
    <ContentTemplate> 
     <div class="form-group row"> 
      <div class="col-sm-6"> 
       <p style="margin: 0 0 5px 0;"><b>Upload File</b></p> 
       <asp:FileUpload ID="imgPhoto" runat="server" /> 
       <br /> 
       <asp:Button ID="btnUpload" Text="Upload" runat="server" OnClick="btnUpload_Click" /> 
       <% if (ViewState["Image"] != null) 
        {%> 
       <a target="_blank" href="<%=ViewState["ImageName"]%>">View Attachment</a> 
       <%} 
        else 
        { %> 
       <asp:Label ID="Label1" runat="server" ForeColor="Red" Text="No File Uploaded"></asp:Label> 
       <%} %> 
      </div> 
     </div> 
    </ContentTemplate> 
</asp:UpdatePanel> 
<asp:UpdateProgress ID="updProgress" AssociatedUpdatePanelID="UpdatePanel1" 
    runat="server"> 
    <ProgressTemplate> 
     <div class="modal"> 
      <div class="center"> 
       <span style="padding-left: 10px"><b>Please Wait..</b></span> 
       <img alt="" src="../images/Preloader_3.gif" width="50" height="50" /> 
      </div> 
     </div> 
    </ProgressTemplate> 
</asp:UpdateProgress> 
<asp:UpdatePanel ID="UpdatePanel1" runat="server"> 
    <Triggers> 
     <asp:AsyncPostBackTrigger ControlID="btnSubmit" EventName="Click" /> 
    </Triggers> 
    <ContentTemplate> 
     <div class="form-group row"> 
      <div class="col-sm-6"> 
       <div class="col-sm-6"> 
        <asp:Button ID="btnSubmit" OnClick="btnSubmit_Click" 
         CssClass="btn btn-primary" OnClientClick="javascript:return btnSubmit();" 
         runat="server" Text="Submit" AutoPostBack="true" /> 
        <a href="assignment.aspx?sid=<%=Request.QueryString["sid"] %>" class="btn btn-default">Cancel</a> 
       </div> 
      </div> 
     </div> 
    </ContentTemplate> 
</asp:UpdatePanel> 
</div> 

代码隐藏

protected void btnSubmit_Click(object sender, EventArgs e) 
    { 
     updProgress.Visible = true; 
     SendEmail(Convert.ToInt32(drpDiv.Text)); 
     updProgress.Visible = false; 
    } 

可能这是一个重复的问题，但我需要解决我的问题

Answer 1

从后面的代码

updProgress.Visible = true; 
updProgress.Visible = false; 

删除此